Developing Pathways to the Synthesis of Low‐Valence Molybdenum Methoxides: Preparation, Characterization, and Redox Chemistry of Dimeric and Tetrameric Molybdenum Alkoxide Clusters

Abstract

The rare Mo=Mo double-bonded dimeric alkoxide complex [Mo 2 Cl 4 (OCH 3 ) 4 (CH 3 OH) 2 ] (1) was prepared by the simple methanolysis reaction of [MoCl 4 (CH 3 CN) 2 ]. It was shown that the dissolution of 1 in thf results in the formation of the [Mo 2 O 2 Cl 4 (OCH 3 ) 2 (thf) 2 ] (2) and [Mo 2 Cl 4 (OCH 3 ) 4 (thf) 2 ] (3) dimers. A novel tetranuclear 10e molybdenum cluster [Mo 4 Cl 4 O 2 (OCH 3 ) 6 (CH 3 OH) 4 ] (4) was synthesized by the spontaneous disproportionation of 1 in methanol. An alternative pathway to 4 based on the redox reaction of Mo 3+ and [a] Institute

A Family of Titanium Complexes with Catechol Ligands: Structural Investigation and Catalytic Application

“…The [NaTi] edges of the [Ti 2 Na 2 ] rhombus are interconnected through µ 2 ‐O atoms of catechol bridging groups, whereas the two triangular [TiNaNa] moieties are each capped by µ 3 ‐bridging oxygen atoms [O(6), O(6A)] located on the opposite sides of the plane of the [Ti 2 Na 2 ] rhombus. It should also be noted that such a structural type is typical of both homo‐ and heterometallic tetranuclear alkoxides and has been observed for a plethora of different oxo complexes , , . The crystal structure of 4 is stabilized by intramolecular hydrogen bonding between the methanol and the catechol ligands [O(5)–H(5) ··· O(7)] characterized by an O(5) ··· O(7) separation of 2.692 Å.…”

Tri-, tetra-, and hexanuclear mixed-valence molybdenum clusters: structural diversity and catalysis of acetylene hydrogenation

“…Recently we have shown that dissolution of 1 in methanol results in the formation of an unexpected producta tetranuclear mixed-valent cluster [Mo +3.5 4 Cl 4 O 2 (OCH 3 ) 6 (CH 3 OH) 4 ] (2) in 32% yield. 9 The latter compound, formed through the obviously complicated reaction pathway, represents the first example of the molybdenum cluster comprising the planar, diagonally bonded {Mo 4 } core. In a pursuit to explore different highly reduced molybdenum alkoxides as catalysts for various multiply bonded substrates hydrogenation, we have started the investigation aiming, firstly, to extend the family of the polynuclear methoxide complexes of the low valence molybdenum whose structural chemistry is limited by just a few examples.…”

“…In a pursuit to explore different highly reduced molybdenum alkoxides as catalysts for various multiply bonded substrates hydrogenation, we have started the investigation aiming, firstly, to extend the family of the polynuclear methoxide complexes of the low valence molybdenum whose structural chemistry is limited by just a few examples. 9,20 Addition of an alkaline agent to the reaction media for the above reaction (1 + CH 3 OH) is a viable means to accomplish the chloride to alkoxide interchange that, being coupled with the ability of -OR ligands to serve as bridging groups and complication of the reaction by molybdenum disproportionation, will open an avenue to the structurally diverse polynuclear alkoxide compounds potentially possessing different types of cluster units. 21 Syntheses and structural study Solution and solid state structures of 3, 7.…”

“…(1) and [Mo 4 Cl 4 O 2 (OCH 3 ) 6 (CH 3 OH) 4 ] (2) were synthesized according to the published procedures. 9 Methanol was dried upon refluxing with magnesium methoxide followed by distillation and was kept in a Schlenk flask over molecular sieves 3 Å. Mg(OCH 3 ) 2 solution was prepared by the reaction of magnesium turnings with methanol. Sodium and europium amalgams were synthesized by the dissolution of the corresponding metal in mercury and stored under argon.…”

“…Motivated by this argumentation, the goal of the present study was to extend the family of the polynuclear methoxide complexes of the low valence molybdenum in order to explore them towards catalytic applications. Thus, we have devised the syntheses of Mo clusters starting from the readily available dimeric complex [Mo 2 Cl 4 (OCH 3 ) 4 (CH 3 OH) 2 ] (1) 9 which proved to be a convenient synthon for the preparation of high-nuclearity molybdenum alkoxides. We have shown that a plethora of novel tri-, tetra-and hexanuclear complexes could be obtained from the reaction of 1 with methanol and stoichiometric amounts of Mg(OCH 3 ) 2 .…”